In a mixed signal circuit, i.e., a circuit that includes both analog and digital signals, a Power-On Reset (POR) circuit is used to ensure that digital logic activity is held at power-up until a supply voltage is ready. During a period of time when the supply voltage is rising to an operational supply voltage level, the POR circuit functions to hold the digital logic in a reset state. More specifically, the POR circuit operates to sense the supply voltage and release a digital logic reset signal when the supply voltage reaches the operational supply voltage level. Therefore, the POR circuit provides a master reset signal for entire mixed signal circuit. If the POR circuit releases the digital logic reset signal too early, the digital logic may operate incorrectly because its supply voltage is not adequate. Therefore, it is necessary to have a POR circuit that operates without fault, regardless of supply voltage behavior during power-up and/or environmental conditions, such as temperature variations.